Flexible well jar



Feb. 8, 1966 R. R. LAWRENCE FLEXIBLE WELL JAR 4 Sheets-Sheet 1 Filed Sept. 2, 1964 ff/cara A. [OW/6066 INVENTOR.

I i L 71.

ATTORNEY Fe 8, 1966 R. R. LAWRENCE FLEXIBLE WELL JAR 4 Sheets-Sheet 2 Filed Sept. 2, 1964 INVENTOR- ATTORNEY Feb. 8, 1966 R. R. LAWRENCE FLEXIBLE WELL JAR 4 Sheets-Sheet 5 7 Filed Sept. 2, 1964 ATTO/F/VEV Feb. 8, 1966 R. R. LAWRENCE 3,233,690

FLEXIBLE WELL J AR Filed Sept. 2, 1964 4 Sheets-Sheet 4 United States Patent 3,233,690 FLEXIBLE WELL JAR Richard R. Lawrence, 125 McCarty, Houston, Tex. Filed Sept. 2, 1964, Ser. No. 394,678 9 Claims. (Cl. 175299) This application is a continuation-in-part of a prior application filed by the same applicant on Jan. 29, 1962, under Ser. No. 169,375.

This invention relates to well jars and more particularly to jarring mechanism designed for connection into a string of well pipe, which is designed to distribute forces produced by flexing movements of the string in a manner to relieve stresses on the mechanism due to such movements, which is adjustable to deliver a jarring impact of predetermined magnitude and which has means for preventing the entrance of foreign matter into the interior of the mechanism.

While not limited to such use, the invention finds particular utility in connection with the drilling and production of wells and in the carrying out of fishing operations for the recovery of lost or stuck objects in well bores.

Jarring mechanism intended for use in well pipe strings usually includes inner and outer telescopingly arranged tubular parts, one of which is adapted to be connected at its upper end to the lower end of an upper section of the string and the other of which is adapted to be connected at its lower end to the upper end of a lower section of the string. The parts are usually closely fitted together for longitudinal sliding movement relative to each other and areformed with impact delivering faces positioned for engagement to deliver an upward impact on the string upon extension of the mechanism and to deliver a downward impact thereon when the same is retracted.

Due to the heavy and rigid construction of the parts, the mechanism is relatively inflexible, so that flexing or gyratory movement of the well pipe during rotation of the same causes the application of great lateral stresses to the parts likely to result in breakage, particularly in the portion of the inner part or mandrel immediately beyond the end of the mandrel which is connected to the well string and which is slidably extended into the free end of the outer part.

The present invention has for an important object the provision of well jar mechanism of the type having inner and outer telescopingly arranged tubular parts designed to be connected into a string of well pipe and constructed for coaction to distribute forces on the mechanism resulting from flexing of the string in a manner to relieve stresses on the parts due to such flexing.

Another object of the invention is the provision in well jarring mechanism of the type referred to of inner and outer telescopingly arranged tubular parts which are constructed to allow a distribution of the forces exerted on the parts in a manner to prevent the concentration of such forces at a location to cause breakage of the parts due to flexing of the string.

A further object of the invention is to provide well jar mechanism of the type referred to in which clearance is provided between the inner and outer parts at the location where the inner part is slidably extended into the free end of the outer part to prevent the concentration of lateral stresses on the parts at a location where the inner part is likely to be broken due to flexing movements of the well string.

A further object of the invention is to provide well jar mechanism having inner and outer telescopingly arranged tubular parts and longitudinally spaced seal forming means between the parts at locations to form therewith a closed fluid chamber within which releasable latch- 3,233,690 Patented F eb. 8, 1966 ing mechanism is disposed for releasably holding the parts against relative longitudinal movement, said seal forming means being movable relative to each other to equalize the pressure in the chamber with the pressure externally thereof.

Another object of the invention is the provision of well jar mechanism of the type referred to wherein the seal forming means is self adjusting longitudinally tomaintain the chamber filled with liquid to prevent the entrance of foreign matter into the chamber.

A further object of the invention is the provision in jarring mechanism of the kind mentioned of means for releasably latching the parts against relative longitudinal movement and means for adjusting the latching means for release upon the application of a predetermined longitudinal force on the string to regulate the magnitude of the impact delivered by the mechanism.

Another object of the invention is to provide latching means in a jar structure of the type referred to which may be released by the exertion of a predetermined longitudinal force on the string to cause the jar to deliver an impact to the string and which may also be released by relative rotation of the parts to allow the mechanism to be operated as a slack joint.

The above and other objects and advantages of the invention will be apparent from the following detailed description of a preferred embodiment thereof when considered in conjunction with the annexed drawings, wherein FIG. 1A is a longitudinal, central, cross-sectional view, on a reduced scale, of the upper portion of the jar mechanism of the invention, showing the relationship of the parts in the extended condition of the mechanism upon the delivering of an upward jarring impact;

FIGURE 13 is a downward construction of the mechanism as illustrated in FIGURE 1A;

FIGURE 2 is a view similar to that of FIGURE 1A showing the relationship of the parts in the retracted condition of the mechanism upon the delivery of a downward jarring impact;

FIGURE 3A is a longitudinal, central, cross-sectional View, on an enlarged scale, of the upper portion of the jarring mechanism of the invention showing details of the structure and arrangement of the parts with the mechanism in its extended, upward jarring impact position;

FIGURE 3B is a downward continuation of the mechanism as illustrated in FIGURE 3A;

FIGURE 4 is a longitudinal, central cros-sectional view, on an enlarged scale, of a lower portion of the jar mechanism of the invention, showing details: of the structure and arrangement of the means by which rotative force is applied to the parts and by which such rotative force is adjusted;

FIGURE 5 is a view similar to that of FIGURE 4 showing details of structure of the means by which the rotative force applying means is adjusted;

FIGURE 6 is a cross-sectional view taken along the line d-ti of FIGURE 4, looking in the direction indicated by the arrows;

FIGURE 7 is a longitudinal, central, cross-sectional view, on an enlarged scale, of an upper portion of the jarring mechanism of the invention, showing details of the structure and arrangement of the parts of the latching mechanism of the same; and

FIGURE 8 is a cross-sectional view, taken along the line 8-45 of FIGURE 7, looking in the direction indicated by the arrows.

Referring now to the drawings in greater detail, the invention is illustrated herein in connection with its application to a string of well pipe, such as is commonly employed in the drilling of oil and gas wells and to which 3 it may be desired to deliver a jarring impact to release the string in the event of sticking of the string in the well bore, or to exert a jarring action on a lost object in the bore to which the lower end of the string has been connected.

The jarring mechanism of the invention comprises inner and outer, telescopingly arranged, tubular parts, generally designated and 12, the outer part, or barrel i2, being conveniently formed in a number of threadably connected sections, such as the sections 14 and 16, which are connected together by an intermediate section 13, whose lower end is positioned to provide downwardly facing internal shoulder forming an anvil.

The inner part, or mandrel in may also be formed in a number of threadably connected sections, such as the upper section 22 and the lower section 24, the upper end of the lower section being externally enlarged to form a hammer 26, positioned for contact With the anvil 20, when the parts are in their extended positions, and the upper end of the upper section 22 having an externally enlarged, internally threaded box portion 28, which also forms a hammer positioned for engagement with the upper end of the outer part when the parts are in their retracted positions.

The outer part is provided at its lower end with an externally threaded pin portion 32, for connection to the upper end of a lower section of well pipe, the box portion 28 of the inner part being adapted for connection to the lower end of an upper section of the well pipe, whereby the jarring mechanism is connected into the string.

Upper and lower packing, generally designated 34 and 34, respectively, is provided, between the inner and outer parts, to form an internal chamber 38, between the parts, which may be filled with a suitable fluid, such as oil.

The upper packing 34 is preferably made up of seal forming elements, such as those indicated at 35, which may be of the chevron, or other suitable type, surrounding the inner part, disposed in an internal enlargement 37, formed in the outer part, and within which a cylindrical actuator, or follower member 39, is slidably positioned in endwise engagement with the packing. The actuator, as best seen in detail in FIGURE 33 is yieldingly urged toward the seal forming elements 35, as by means of a coil spring 4-1 which bears at one end against one end of the actuator and whose other end is seated on an internal shoulder 4-3 formed by one end of the intermediate section 18 of the outer part, whereby the actuator exerts a compressive force on the elements to urge the same into tight sealing engagement with the parts.

The lower packing 3'4 is of the same construction as the upper packing 34, described above, with the parts thereof reversed, the actuator 39 being yieldingly urged by the spring 41" in the opposite direction to that in which the actuator 39 is urged by the spring 41. By this arrangem'ent it will be apparent that the actuators 39 and 3% are yieldingly urged by the springs in opposite directions away from each other. Moreover, the upper and lower packin'gs may move inwardly of the chamber in response to the high fluid pressure often encountered in wells, thus preventing the entrance of foreign matter into the chamber from the exterior which might occur if the chamber is not maintained completely filled.

Within the chamber 38', the parts are provided with latching mechanism illustrated in detail in FIGURES 7 and 8, which is engageable by relative rotation of the parts in one direction to hold the parts against relative longitudinal movement and disengageable by relative r0 tation of the parts in the other direction to allow such longitudinal movement. The latching mechanism in cludes peripherally spaced, external longitudinal grooves in the inner part, such as that indicated at 46 and longitudinally spaced sets of peripherally extending, longitudinally spaced notches 42 opening into the grooves and into which longitudinally spaced rollers i i, rotatably mounted on theonter part are movable by relative rotation of the parts to hold the parts against relative longitudinal movement.

Suitable means, such as the coil springs 46 are provided, within the chamber 38, each of which is connected at one end to the inner part and at the other end to the outer part to yieldingly urge the parts in a direction of relative rotation to hold the rollers 44 in the notches 42.

The side Walls of the notches 42 preferably converge toward the bottoms of the notches or are flared outwardly somewhat, so that upon the exertion of a predetermined longitudinal force on the parts tending to move the parts longitudinally relative to each other, relative rotational movement will be imparted to the parts to cause the rollers to roll out of the notches into grooves 40, whereupon the parts will move longitudinally relative to each other with a snapping action to deliver an impact to the anvil or to the upper end 3d of the outer part, to produce a jarring action on the string.

Means is provided for adjusting the rota'tive force ap-' plied to the inner and outer parts by the springs 46', as best illustrated in detail in FIGURES 4, 5 and 6. For this purpose the inner part has a holding portion 64, which is of somewhat smaller external diameter than the latching portion of the inner part above, and is provided with peripherally spaced, longitudinal grooves 66, best shown in FIGURE 6.

Within the outer part a narrow stop ring 63 surrounds the portion 64 of the inner part, which ring is secured to the outer part by pins, such as those shown at 70, extending into peripherally spaced holes in the ring and attached to plugs 72', extending into peripherally spaced holes 74 in the outer part and attached thereto as by means of welding, screw threading, or the like. By this means the stop ring is held against longitudinal movement in the outer part.

The coil springs 46 surround the inner part below the stop ring 68, each spring being provided with an upper end collar or sleeve portion 78 and a lower collar or sleeve portion ill). The upper sleeve or collar 78 of the upper one of the springs 46 abuts against the lower face or the ring as and is provided with peripherally spaced, internal rollers 82 rotatably mounted on the barrel in position for rolling contact with the mandrel in the longitudinal grooves as to hold the springs against rotation relative to the mandrel.

The lower collar or sleeve is formed with peripherally spaced holes 84', into which pins as carried by the barrel are extended. The pins 86 may be attached to the barrel, by means of plugs 33 extending into suitable holes in the barrel and secured thereto as by welding, screw threading, or the like. By this arrangement, it will be apparent that the collars 80 of the springs may be rotated clockwise about the mandrel with the pins 36 removed and the upper collars 78 held against rotation about the mandrel by the rollers 82 in the grooves es. When the springs have been thus wound up to the desired extent the pins as are inserted through the holes in the barrel into selected ones of the holes $4 to hold the springs under tension. With the springs thus tensioned and secured to the barrel and mandrel it will be apparent that the springs will exert relative rotational forces on the barrel and mandrel tending to hold the rollers 44 in the notches 42 of the mandrel to releasably latch the mandrel against longitudinal movement in the barrel.

It will be apparent that by this mechanism either an upward or a downward impact may be delivered to the string, while at the same time the parts have only limited relative rotational movement so that the string may be rotated in either direction.

In operating the jar, it is connected into a drilling or operating string and lowered into the well. When the jar is not being operated to deliver an impact, the rollers 44 will ordinarily be in the notches 2-2 of the mandrel, in which they will be yieldingly held by the tension of .livered by the jar.

the springs 46, thus releasably latching the jar preparatory to operation of the jar to deliver an impact either upwardly or downwardly on the string. When it is desired to deliver an upward impact on the string, the upward pull on the string may be increased until the tension on the springs 46 is overcome to allow relative rotation of the barrel and mandrel in a direction to cause the rollers 44 to roll out of the notches 42 into the grooves 40, whereupon the mandrel will be suddenly moved upwardly with a snapping action to engage the upper end of the portion 26 of the mandrel with the lower end of the anvil 20 to deliver an upward impact. After the jar has been operated to exert such an upward impact, the upward pull on the string may be reduced to allow the mandrel to move downwardly in the barrel, whereupon the rollers 44 will again enter the notches 42 to latch the jar preparatory to actuation of the same to deliver another impact.

It will be apparent that because of the outwardly flaring shape of the notches 42, the rollers, in engagement with the sides of the notches, will exert a force tending to impart relative rotation to the barrel and mandrel upon the exertion of a pull on the string sufficient to overcome the tension of the springs 46, to move the rollers 44 out of the notches into the grooves 4%, to permit sudden relative longitudinal movement of the barrel and mandrel.

When it is desired to deliver a downward impact with the jar, the upward pull on the string may be reduced sufiiciently to allow the string to exert a downward force on the mandrel sutficient to overcome the tension of the springs 46, whereupon the rollers 44 will move out of the notches 42 into the grooves 40, to allow the mandrel to move suddenly downwardly in the barrel to ber 23 with the upper end of the anvil 30. When the downward impact has been thus delivered, the mandrel may again be moved upwardly by an upward pull on the string to allow the rollers 44 to again enter the notches 42 to reset the latching mechanism preparatory to further jarring operation.

The longitudinal force which must be exerted to release the latching mechanism of the jar may, of course, be adjusted as desired by adjusting the tension of the springs 46, so that a predetermined impact may be de- The amount of rotative force or torque required to release the latching mechanism may also be varied by increasing the number of the springs 46 which are used in the jar, as many such springs being added as may be desired.

It will also be apparent that the jar may be operated as a slack joint by applying a counterclockwise rotative force to the mandrel to move the rollers 44 out of the notches into the grooves 46 so that the jar may be operated by upward or downward movement of the string, without the snapping action which takes place when the latching mechanism is released solely by a longitudinal force-exerted on the mandrel.

In the event that it should be desired to increase the impact delivered by the jar during the operation of the apparatus, this may be accomplished without removing the jar from the well by exerting a rotative force on the string in the latching direction to increase the amount of longitudinal force which must be applied to cause the latching mechanism to release, so that a greater impact will be obtained.

In jarring mechanism of this kind, the inner and outer parts are closely fitted together for relative longitudinal sliding movement, so that the mechanism has little or no lateral flexibility, and under the conditions usually encountered in well drilling, in which considerable flexing of the string takes place during rotation of the same in the well bore, the working of the mandrel, or inner part sometimes results in breaking of the same, particularly in the region of the internally threaded box portion 28.

The present invention is designed to avoid such breakage by the provision of means for allowing limited movement of the parts laterally relative to each other in the region where the upper portion of the inner part slides telescopingly in the upper end portion of the outer part. For this purpose the upper portion of the outer part 12 is formed with an internal enlargement 48 located above the packing 34, and the upper portion of the inner part 10 which is slidably extended into the enlargement 48 is externally enlarged, as shown at 50.

The inner part has a portion immediately below the externally enlarged portion 5!) thereof which is of smaller diameter as compared with the portion 50 and the diameter of the portion 50 is substantially smaller than the internal diameter of the portion 48 of the outer part, so that the inner part may move laterally relative to the outer part.

The outer part is provided in the internally enlarged portion 48 with longitudinally spaced internal annular grooves 52 within which annular resilient elements 54 formed of rubber, neoprene, or the like, are disposed, whose inner peripheries are positioned for engagement with the outer surface of the portion 50 of the inner part to yieldingly resist lateral movement of the inner part.

Between the resilient elements or rings 54, the outer part may be provided with openings 56,. as shown in FIGURE 3A, through which fluid may enter and escape from the interior of the outer part, and the outer part may also have an opening 58 near the lower end of the portion 48 for a similar purpose.

The lengths of the portions 43 and Sit and the distances between the hammer portions 26 and 28 and anvil or impact receiving faces 2i) and 3d is preferably such that the lower end of the portion 50 is always located inwardly of the innermost one of the rings 54.

It will be apparent that when the jarring mechanism, constructed as described above, is connected into a string of pipe for rotation therewith in a well bore, the portion 50 of the inner part may move laterally .in the portion 48 of the outer part to distribute the forces exerted on the parts due to gyratary movements of the pipe string, to prevent concentration of the stresses on the parts at a location likely to cause breakage of the inner part in the region immediately below the box portion 28, regardless of the relative longitudinal positions of the parts.

It will be understood that the invention is not necessarily limited to use in jarring mechanism of the type disclosed herein and is capable of use with well jars having latching mechanism of other kinds than that disclosed in said prior application, which is included herein by way of example onlyv Having thus clearly shown and described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. In a well jar inner and outer telescopingly arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to the lower end of an upper section of a string of well pipe, means for connecting the lower end of the other part to the upper end of a lower section of said string, said parts having elongated portions positioned to form an annular fluid chamber between the parts, sealing means positioned between the parts at the ends of the chamber, said parts having elongated portions radially spaced from each other to allow relative lateral movement between the parts at a location externally of the chamber, yieldable means between the parts at said location positioned for coaction with the parts to yieldingly resist such relative lateral movement, and means on the parts positioned for coaction upon relative longitudinal movement of the parts to deliver a longitudinal impact to the string.

2. The well jar set forth in claim 1 wherein said sealing means are self-adjusting longitudinally within the chamber.

3. In a well jar inner and outer concentrically arranged tubular parts movable longitudinally relative to each other, means for connecting one of the parts to an operating string, means for connecting the other part to an object stuck in a well bore, coacting impact faces on the parts positioned for contact when the parts reach the limit of their relative longitudinal movement in one dircction, interengageable means on the parts positioned for interengagement upon relative rotational movement of the parts with said faces out of contact to hold the parts against relative longitudinal movement and for disengagement upon relative rotational movement of the parts in the other direction to allow such longitudinal movement, yieldable means positioned for coaction with the parts to yieldingly resist relative rotational movement of the parts in said other direction, said interengageable means having curved surfaces shaped for coaction to impart relative rotational movement to the parts in said other direction against the resistance of said yieldable means to cause sudden disengagement of said interengageable means upon the exertion of a predetermined longitudinal force on the parts tending to impart relative longitudinal movement to the parts in a direction to move said faces into contact, means for adjusting the resistance of said yieldable means to such relative rotational movement to vary the longitudinal force required to cause disengagement of said interengageable means, said parts having elongated portions positioned to form an annular fluid chamber between the parts, sealing means positioned between the parts at the ends of the chamber, said parts having elongated portions radially spaced from each other to allow relative lateral movement between the parts at a location externally of the chamber and yieldable means between the parts at said location positioned for coaction with the parts to yieldingly resist such relative lateral movement.

4. In a well ja-r inner and outer concentrically arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to an operating string, means for connecting the other part to an object stuck in a well bore, impact faces on the parts positioned for contact when the parts reach the limit of their relative longitudinal movement in one direction, interengageable means on the parts positioned for coaction in one position of relative longitudinal movement to hold the parts against relative rotation and in another position of relative longitudinal movement with said faces out of contact to allow limited relative rotation of the parts and shaped for coaction when the parts are in one position of relative rotation to hold the parts against relative longitudinal movement and when the parts are in another position of relative rotation to allow such longitudinal movement, yieldable means positioned for coaction to yieldingly resist relative rotation of the parts away from said one position of relative rotation, means for adjusting the resistance of said yieldable means to such relative rotational movement of the parts, said parts having elongated portions positioned to form an annular fluid chamber between the parts, sealing means positioned between the parts at the ends of the chamber, said parts having elongated portions radially spaced from each other to allow relative lateral movement between the parts at a location externally of the chamber and yieldable means between the parts at said location positioned for coaction with the parts to yieldingly resist such relative movement.

5. In a well jar inner and outer telescopingly arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to an operating string, means for connecting the other part to an object stuck in a well bore, coacting impact faces on the parts positioned for contact when the parts reach the limit of their relative longitudinal movement in one direction, interengageable means on the parts positioned for coaction to hold the parts against movement out of one positi n of relative rotation of the parts when the parts are in one position of relative longitudinal movement and to allow relative rotational movement of the parts to another position of relative rotation when the parts are in another position of relative longitudinal movement with said faces out of contact, said interengageable means being shaped for coaction to hold the parts against relative longitudinal movement when the parts are in said other position of relative rotation and to allow such longitudinal movement when the parts are in said one position of relative rotation, yieldable means positioned for coaction with the parts to yieldingly resist movement of the parts from said other to said one position of relative rotation, means for adjusting the resistance of said yieldabie means to such relative rotational movement of the parts, said parts having elongated portions positioned to form an annular fluid chamber between the parts, sealing means positioned between the parts at the ends of the chamber, said parts having elongated portions radially spaced from each other to allow relative lateral movement between the parts at a location externally or" the chamber and yieldable means between tre parts at said location positioned for coaction with the parts to yieldingly resist such relative lateral movement.

6. In a well jar inner and outer telescopingly arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to an operating string, means for connecting the other part to an object stuck in a well bore, coacting impact faces on the parts positioned for contact when the parts reach the limits of their relative longitudinal movement in either direction, said inner part having an external longitudinal groove and a laterally extending notch opening into the groove, and roller means on the outer part extending into and rotatably engageable with the inner part in the groove in position to enter the notch upon relative rotation of the parts in one direction when the parts are in one poistion of relative longitudinal movement between said limits to hold the parts against relative longitudinal movement, yieldable means positioned for coaction with the parts to yieldingly resist relative rotational movement of the parts in the other direction, the side walls of said notch being shaped for coaction with said roller means to apply a force to the parts tending to rotate the parts in said other direction upon the exertion of a force on the parts tending to move the parts longitudinally relative to each other away from said one position, and adjustable means connecting said yieldable means to one of said parts for adjusting the resistance of said yieldable means to such relative rotational movement of the parts.

7. In a well jar inner and outer telescopingly arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to an operating string, means for connecting the other part to an object stuck in a well bore, coacting impact faces on the parts positioned for contact when the parts reach the limits of their relative longitudinal movement in either direction, said inner part having an external longitudinal groove and a laterally extending notch opening into the groove, and roller means on the outer part extending into and rotatable engageable with the inner part in the groove in position to enter the notch upon relative rotation of the parts in one direction when the parts are in one position of relative longitudinal movement between said limits to hold the parts against relative longitudinal movement, yieldable means positioned for coaction with the parts to yieldingly resist relative rotational movement of the parts in the other direction, said notch having a curved bottom wall conforming to the shape of and engageable with the periphery of said roller means when the roller means reaches the limit of its inward movement in the notch and outwardly flaring side walls, merging at their outer ends with one side Wall of said groove for coaction with said roller means to apply a force to the parts tending to rotate the parts in said other direction to cause a sudden release of the roller means from the notch upon the exertion of a predetermined force on the parts tending to move the parts longitudinally relative to each other away from said one position, and adjustable means connecting said yieldable means to one of said parts for adjusting the resistance of said yieldable means to such relative rotational movement of the parts.

8. In a well jar inner and outer telescopingly arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to the lower end of an upper section of a string of well pipe, means for connecting the lower end of the other part to the upper end of a lower section of said string, said parts having elongated portions positioned to form an annular fluid chamber between the parts, sealing means positioned between the parts at the ends of the chamber, said parts having elongated portions radially spaced from each other to allow relative lateral movement between the parts at a location externally of the chamber, yieldable means between the parts at said location positioned for coaction with the parts to yieldingly resist such relative lateral movement, and means on the parts positioned within said annular fluid chamber for coaction upon relative longitudinal movement of the parts to deliver a longitudinal impact to the string.

9. In a well jar inner and outer telescopingly arranged tubular parts movable longitudinally relative to each other, means for connecting one of said parts to the lower end of an upper section of a string of Well pipe, means for connecting the lower end of the other part to the upper end of a lower section of said string, said parts having elongated portions positioned to form an annular fluid chamber between the parts, sealing means positioned between the parts at the ends of the chamber, said parts having elongated portions radially spaced from each other to allow relative lateral movement between the parts at a location externally of the chamber, yieldable means between the parts at said location positioned for coaction with the parts to yieldingly resist such relative lateral movement, coacting impact faces on the parts positioned for contact when the parts reach the limits of their relative longitudinal movement, and holding means positioned within said annular fluid chamber for holding said parts against relative longitudinal movement upon relative rotation of the parts in one direction and permitting relative longitudinal movement of the parts upon relative rotation of said parts in the other direction and yieldable means positioned for coaction with the parts to yieldingly resist relative rotational movement of the parts in the other direction.

References Cited by the Examiner UNITED STATES PATENTS 1,899,438 2/1933 Grant -299 2,056,496 10/1936 White 175-304 2,101,968 12/1937 Wickersham 175-304 2,474,459 6/1949 Beck 175-304 2,562,321 7/1951 Lowe 175-304 2,721,056 11/1955 Storm 175-297 2,819,876 1/1958 Ransom 175-294 CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN HERSH, Examiner. 

1. IN A WELL JAR INNER AND OUTER TELESCOPINGLY ARRANGE TUBULAR PARTS MOVABLE LONGITUDINALLY RELATIVE TO EACH OTHER, MEANS FOR CONNECTING ONE OF SAID PARTS TO THE LOWER END OF AN UPPER SECTION OF A STRING OF WELL PIPE, MEANS FOR CONNECTING THE LOWER END OF THE OTHER PART TO THE UPPER END OF LOWER SECTION OF SAID STRING, SAID PARTS HAVING ELONGATED PORTIONS POSITIONED TO FORM AN ANNULAR FLUID CHAMBER BETWEEN THE PARTS, SEALING MEANS POSITIONED BETWEEN THE PARTS AT THE ENDS OF THE CHAMBER, SAID PARTS HAVING ELONGATED PORTIONS RADIALLY SPACED FROM EACH OTHER TO ALLOW RELATIVE LATERAL MOVEMENT BETWEEN THE PARTS AT A LOCATION EXTERNALLY OF THE CHAMBER, YIELDABLE MEANS BETWEEN THE PARTS AT SAID LOCATION POSITIONED FOR COACTION WITH THE PARTS TO YIELDINGLY RESIST SUCH RELATIVE LATERAL MOVEMENT, AND MEANS ON THE PARTS POSITIONED FOR COACTION UPON RELATIVE LONGITUDINAL MOVEMENT OF THE PARTS TO DELIVER A LONGITUDINAL IMPACT TO THE STRING. 